Magnetometers, or sensors for detecting magnetic fields, are well known in the prior art. Such prior art magnetometers can consist of a small, magnetically susceptible core wound by two coils of wire. An alternating electrical current can be passed through one coil, which can induce an electrical current in the second coil, and this output current, mediated by the magnetically susceptible core, can be measured by a detector. In a magnetically neutral background, the input and output currents will match. However, when the core is exposed to a background field, it can be more easily saturated in alignment with that field and less easily saturated in opposition to it. Hence the alternating magnetic field, and the induced output current, will be out of phase with the input current. The extent to which this is the case will depend on the strength of the background magnetic field. Often, the current in the output coil can be integrated to yield an output analog voltage, which can be proportional to the magnetic field. But for these types of sensors, an applied current is required.
Multiferroics, or materials that simultaneously exhibit magnetic and ferroelectric orders, are also known in the prior art. These materials can often also be termed as magnetoelectrics, because the material magnetic and electric order parameters are coupled. Multiferroics can be technologically important, as they can have two or more switchable states, like a magnetization state that may be switched with an electric field, and a spontaneous electric polarization state that may be switched with a magnetic field. Such materials can play a vital role in the design of electric-field controlled ferromagnetic resonance devices, actuators, and variable transducers with magnetically-modulated piezoelectricity etc. Additionally, magnetoelectrics can also have tremendous potential for use in storage devices where writing and read-out can be carried out by both/either of electric or magnetic fields. In sum multiferroics can be important to any device where it is preferable to use an electric field, instead of electric current, to operate the device.
Interestingly, recent experimental and theoretical studies explicitly reveal novel behavior and exciting physics in multiferroic materials. Being of great interest, and being motivated by on-chip integration in microelectronic devices, nanostructured composites of ferroelectric and magnetic oxides deposition as a thin film on a substrate are being increasingly studied. Such initiatives are expected to lead to a better understanding of the basic nature of magneto-electric coupling so that the magneto-electric coupling can be used for specialized applications.
Research on the optimization of the performance of magnetometers that use ferromagnetic cores, and on nonlinear oscillators for electric field sensing based on ferroelectric capacitors continues to be ongoing in the prior art. However, up until now, minimization of the power demand for magnetometers (which is a key optimization feature) has been limited due to the intrinsic properties of the device, which must be “current driven” in order to ensure a proper magnetization of the core. Because the prior art magnetometers need an applied current to operate, the power budget for the prior art device cannot be reduced below a certain threshold, which can further place limits on both the size and the sensitivity of the device.
The availability of materials whose magnetization can be quantified not via an applied current but by using an electric field would represent a major breakthrough in the field given the inherent low power (“nearly zero power”) of this approach. This is the promise given by multiferroic materials that are therefore hysteretic in both the electric and the magnetic domain. An adequate knowledge of these materials and a suitable exploitation of their unique features could therefore lead to novel devices that can detect weak low frequency magnetic fields and that demand a negligible amount of power to operate.
In view of the above, it is an object of the present invention to provide a sensor that can incorporate multiferroic materials to detect electric fields or magnetic fields using the same underlying setup. Another object of the present invention is to provide a sensor that can incorporate multiferroic materials to measure magnetic fields using an applied electric field instead of an applied electric current. Still another object of the present invention is to provide a sensor that can incorporate multiferroic materials that have an extremely low power footprint to accomplish the measurement of electric fields and magnetic fields. Another object of the present invention to provide a sensor that can incorporate multiferroic materials, which can be easy to manufacture, and which can be used in a cost-efficient manner. Finally, the unique coupling configuration affords enhanced target signal resolution; in fact the resolution can be shown to improve with N the number of coupled circuit block.